With respect to the cited paper
"The astonishing 63Ni radioactivity reduction in radioactive wastes
by means of ultrasounds application"
· Fabio Cardone2,3 · Pasquale Avino4
Having done a lot of ultrasonication, I would like to see the before/after sonication elemental analysis of sample of various corrosivities NOT containing radionuclides. In my experience sonotrode erosion is common (nay, inevitable), and would possibly account for a good deal of the observed increases in the concentrations of many elements in sonicated material vs unsonicated.
This is out of interest, not to decry interesting results found in other cavitation experiments